As a solar power generation device that includes a solar cell element in a portion of a light guide and generates power by allowing light propagating through the inside of the light guide to be incident on the solar cell element, a solar power generation device (solar energy recovery window) described in PTL 1 is known.
The solar power generation device is configured such that some of the solar light incident from a main surface of the light guide is allowed to propagate through the inside of the light guide and to be guided to the solar cell element. The light guide contains a phosphor (fluorescent substance). The phosphor absorbs the solar light (incident light) incident on the light guide and is excited and then emits light. Power is generated by radiation light (fluorescence) from the phosphor at this time propagating through the inside of the light guide and being incident on the solar cell element.
In such a solar power generation device, the light emitting capability of the phosphor may be a factor that determines the power generation amount. Further, in order to increase the power generation amount of the solar power generation device, it is desirable that a phosphor capable of absorbing light having a sufficiently long wavelength is used, that is, it is important to select an appropriate phosphor.
Various kinds of materials have been investigated as a phosphor so far, and, for example, a compound represented by the following formula (9)-1 (hereinafter, simply written as the “compound (9)-1”) is disclosed in NPLs 1 and 2.
